<?php
/**
 * CDataProvider is a base class that implements the {@link IDataProvider} interface.
 *
 * Derived classes mainly need to implement three methods: {@link fetchData},
 * {@link fetchKeys} and {@link calculateTotalItemCount}.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CDataProvider.php 3001 2011-02-24 16:42:44Z alexander.makarow $
 * @package system.web
 * @since 1.1
 */
abstract class CDataProvider extends CComponent implements IDataProvider
{
    private $_id;
    private $_data;
    private $_keys;
    private $_totalItemCount;
    private $_sort;
    private $_pagination;

    /**
     * Fetches the data from the persistent data storage.
     * @return array list of data items
     */
    abstract protected function fetchData();
    /**
     * Fetches the data item keys from the persistent data storage.
     * @return array list of data item keys.
     */
    abstract protected function fetchKeys();
    /**
     * Calculates the total number of data items.
     * @return integer the total number of data items.
     */
    abstract protected function calculateTotalItemCount();

    /**
     * Returns the ID that uniquely identifies the data provider.
     * @return string the unique ID that uniquely identifies the data provider among all data providers.
     */
    public function getId()
    {
        return $this->_id;
    }

    /**
     * Sets the provider ID.
     * @param string $value the unique ID that uniquely identifies the data provider among all data providers.
     */
    public function setId($value)
    {
        $this->_id=$value;
    }

    /**
     * Returns the pagination object.
     * @return CPagination the pagination object. If this is false, it means the pagination is disabled.
     */
    public function getPagination()
    {
        if($this->_pagination===null)
        {
            $this->_pagination=new CPagination;
            if(($id=$this->getId())!='')
            $this->_pagination->pageVar=$id.'_page';
        }
        return $this->_pagination;
    }

    /**
     * Sets the pagination for this data provider.
     * @param mixed $value the pagination to be used by this data provider. This could be a {@link CPagination} object
     * or an array used to configure the pagination object. If this is false, it means the pagination should be disabled.
     */
    public function setPagination($value)
    {
        if(is_array($value))
        {
            $pagination=$this->getPagination();
            foreach($value as $k=>$v)
            $pagination->$k=$v;
        }
        else
        $this->_pagination=$value;
    }

    /**
     * Returns the sort object.
     * @return CSort the sorting object. If this is false, it means the sorting is disabled.
     */
    public function getSort()
    {
        if($this->_sort===null)
        {
            $this->_sort=new CSort;
            if(($id=$this->getId())!='')
            $this->_sort->sortVar=$id.'_sort';
        }
        return $this->_sort;
    }

    /**
     * Sets the sorting for this data provider.
     * @param mixed $value the sorting to be used by this data provider. This could be a {@link CSort} object
     * or an array used to configure the sorting object. If this is false, it means the sorting should be disabled.
     */
    public function setSort($value)
    {
        if(is_array($value))
        {
            $sort=$this->getSort();
            foreach($value as $k=>$v)
            $sort->$k=$v;
        }
        else
        $this->_sort=$value;
    }

    /**
     * Returns the data items currently available.
     * @param boolean $refresh whether the data should be re-fetched from persistent storage.
     * @return array the list of data items currently available in this data provider.
     */
    public function getData($refresh=false)
    {
        if($this->_data===null || $refresh)
        $this->_data=$this->fetchData();
        return $this->_data;
    }

    /**
     * Sets the data items for this provider.
     * @param array $value put the data items into this provider.
     */
    public function setData($value)
    {
        $this->_data=$value;
    }

    /**
     * Returns the key values associated with the data items.
     * @param boolean $refresh whether the keys should be re-calculated.
     * @return array the list of key values corresponding to {@link data}. Each data item in {@link data}
     * is uniquely identified by the corresponding key value in this array.
     */
    public function getKeys($refresh=false)
    {
        if($this->_keys===null || $refresh)
        $this->_keys=$this->fetchKeys();
        return $this->_keys;
    }

    /**
     * Sets the data item keys for this provider.
     * @param array $value put the data item keys into this provider.
     */
    public function setKeys($value)
    {
        $this->_keys=$value;
    }

    /**
     * Returns the number of data items in the current page.
     * This is equivalent to <code>count($provider->getData())</code>.
     * When {@link pagination} is set false, this returns the same value as {@link totalItemCount}.
     * @param boolean $refresh whether the number of data items should be re-calculated.
     * @return integer the number of data items in the current page.
     */
    public function getItemCount($refresh=false)
    {
        return count($this->getData($refresh));
    }

    /**
     * Returns the total number of data items.
     * When {@link pagination} is set false, this returns the same value as {@link itemCount}.
     * @param boolean $refresh whether the total number of data items should be re-calculated.
     * @return integer total number of possible data items.
     */
    public function getTotalItemCount($refresh=false)
    {
        if($this->_totalItemCount===null || $refresh)
        $this->_totalItemCount=$this->calculateTotalItemCount();
        return $this->_totalItemCount;
    }

    /**
     * Sets the total number of data items.
     * This method is provided in case when the total number cannot be determined by {@link calculateTotalItemCount}.
     * @param integer $value the total number of data items.
     * @since 1.1.1
     */
    public function setTotalItemCount($value)
    {
        $this->_totalItemCount=$value;
    }
}
